Work piece transporting mechanism for broaching machine



R. J. FRETER 2,955,516

WORK PIECE TRANSPORTING MECHANISM FOR BROACHING MACHINE,

Oct. 11, 1960 2 Sheets-Sheet 1 Original Filed Nov. 12. 1953 INVENTOR.Roy J. Fre fer:

ATTORNEY O u 4 U a w B 8 l l M 8 l 5 Oct. 11, 1960 R. J. FRETER2,955,516

WORK PIECE TRANSPORTING MECHANISM FOR BROACHING MACHINE Original FiledNov. 12. 1953 2 Sheets-Sheet 2 I 95 78 I 5 74 9 13 w s 46 I 6 im w rgbs7 INVENTOR.

AcyJ fiefe/r By W W2 6V5 ATTORNEY WORK PIECE TRANSPORTING MECHANISM FORBROACHING MACHINE Roy J. Freter, 250 W. Riverglen Drive, Worthington,Ohio Continuation of abandoned application Ser. No. 587,296, May 25,1956, which is a division of application Ser. No. 391,516, Nov. 12,1953, now Patent No. 2,751,823, dated June 26, 1956. This applicationMay 21, 1958, Ser. No. 736,926

3 Claims. (CI. 90-56) The present invention relates generally to metalworking machines and more particularly to a novel work piecetransporting mechanism for a continuous broaching machine for broachingwork pieces at a high rate of production.

This application is a continuation of my copending application, SerialNumber 587,296, filed May 25, 1956,

States Patent now abandoned, which application is a division of myapplication Serial Number 391,516, filed November 12, 1953, now PatentNumber 2,751,823, dated June 26, 1956.

The present novel work piece transporting mechanism is incorporated in acontinuous broaching machine disclosed in the above mentioned patentwhich broaching machine incorporates a novel basic concept of surfacebroaching work pieces, with far greater speed than could heretofore ,beattained by prior production broaching v constructions.

An aspect of the present invention consists of providing novel workpiece transporting mechanism for a broaching machine which cyclicallymoves a broaching means along a cutting path, said mechanism serving toefficiently move and position work pieces relative to the cutting pathin synchronization with said cyclical movement.

Another aspect of the present invention resides in providing a workpiece transporting mechanism, in a machine of the type described, whichmechanism is interi mittently stationary to permit the operator toproperly and safely load the work pieces.

Another aspect of the invention relates to the economy with which thepresent work piece transporting mechanism can beretooled. This is ofparticular significance I in small volume production runs where highretooling costs prohibit the use of conventional production broachingmachines.

As each work holder requires a custom fixture for the particular workpiece being run, the fixture cost, in toolmits the application ofproduction broaching to jobs which were heretofore assigned to sloweroperations such as milling and grinding.

Another aspect of the present invention resides in the provision of awork piece transporting mechanism which permits a broaching machine tobe operated with precision at the high operational speeds achieved bythe continuous broaching machine disclosed in the above men- 'tionedpatent.- Conventional hydraulicmachines of today are designed to surfacebroach steel of medium high carbon content (S.A.E. 1035) at a rate ofcutter speed travel of only seventy feet per minute. This speedlimitation is not governed by the operators ability to keep up with themachine, but rather by the inherent design of such present day machineswhich are designed by the limitations of tradition which set forthmaximum rates of cutter speed at seventy feet per minute. The presentinventor has discovered that these traditional limitations are entirelyin error. Exhaustive broach tests have proven that excellent broach lifeis obtained, employing broaches of regular high speed steel, at speedsof cutter travel in excess of two hundred and fifty feet per minute.

Another aspectof the invention consists of achieving precision tolerancecontrol by accurately locating the work piece holders, relative to thecutting path, at the broaching station.

As further aspects of the present invention, the present novel workpiece transporting mechanism consists of simple structure which can bereadily serviced and repaired. A machine incorporating the mechanism canbe readily retooled by set-up men as all fixtures are out in the openand hence accessible. Moreover, the present mechanism is compact,particularly from the standpoint of floor space occupied; hence savingsin plant overhead are realized as a result of the savings in floor spacewhich result when a broaching machine incorporating the mechanism of theinvention is employed.

Further objects and advantages of the present inven-.

tion will be apparent from the following description, reference beinghad to the accompanying drawings wherein a preferred form of embodimentof the invention is clearly shown.

In the drawings:

Figure l is a front elevational view, partially in section, of abroaching machine which incorporates the work piece transportingmechanism of the present invention, with the section being takensubstantially along the line 1-1 of Figure 3;

Figure 2 is a side elevational view, partially in section, of thebroaching machine and mechanism of Figure 1, with the section beingtaken substantially along the line 2-2 of Figure 3;

Figure 3 is a top elevational view, partially in section of thebroaching machine and mechanism of the preceding figures, with thesection being taken substantially along the line 33 of Figure 2;

Figure 4 is a partial perspective view showing a broach holder and aslide for guiding same, said holder and slide being utilized inconnection with the machine and mechanism of the preceding figures;

Figure 5 is a schematic view of a means for accurately locking the workpiece transporting mechanism of the present invention, at variouspositions of movement, just prior to each passage of the broaching meansalong the cutting path;

Figure 6 is a top elevational view of the work piece transportingmechanism and broach slide of the present invention showing fixtures forholding work pieces and associated apparatus for opening and closing thefixtures at various positions of movement of the mechanism; and

Figure 7 is a side elevational view corresponding to Figure 6 and takenpartially in section along the line 77' of Figure 6.

Referring next to the drawing, and particularly to Figures 1, 2, and 3which show a broaching machine and work piece transporting mechanism incorresponding elevational views, a main frame is indicated general- 'lyat 10. The frame 10 carries a pair of spaced supports 12 and 13 securedto a bottom plate 15.

A pair of vertically extending spaced side plates 18 and 19 are based onthe spaced supports 12 and 13, re-

Patented Oct. 11, 1960 spectively, with the side plates 18 and 19forming a mounting means for a broach transporting apparatus. The broachtransporting apparatus may be formed as an endless'carrier, or chain 21,carried by an uppersprocket 24 and; a lower sprocket '25. Upper sprocket24 is keyed to a shaft 26 journaled in bearing blocks 27 which aremounted on flanges 28 provided on the side plates 18 and 19. Lowersprocket 25, which drives the chain 21, is keyed to shaft 30'journaledin bearing blocks 31 which are mounted on flanges 32 provided on thesupports 12 and 13.

As is best seen in Figures 1 and 3, an end of shaft 30 is engaged anddrivenby a variable speed drive which includes a prime mover 35. As thepresent in.- vention contemplates the cyclical movement of a broachingmeans along a predetermined path, to be referred to herein as thecutting path, a broaching means is provided for the present structure inthe form of broach carriage assemblies, indicated generally at 37. Assuch broach carriage assemblies are mounted at spaced intervals alongendless carrier 21, it will be seen that a broaching means is cyclicallytransported along the cutting path, which path represents a portion ofthe entire path of broaching means travel. Moreover, it is seen that therate of speed at which the broaching means travels along the cuttingpath, and the cyclical rate at which the broaching means traverses thecutting path, can be readily varied by changing the setting of thevariable speed drive 34.

The broaching machine, described above, incorporates a novel work piecetransporting means constructed according to the present invention andadapted for sequentially transporting Work pieces into the above definedcutting path. Such work piece transporting means may be formed as aturntable, indicated generally at 40 in the figures, mounted forrotation about a vertical axis by means of a shaft 42 journaled in topplate 44 of frame 10.

Turntable 40 is sequentially rotated through a predetermined angle ofrotation, and stopped at predetermined positions such that work pieces46, 47, 48, and 49, best seen in Figure 6, are sequentially moved intoand out of the cutting path of the broaching means. The work pieces 46,47, 48, and 49 are carried on turntable 40 by a plurality of clampingmeans indicated generally at 51, 52, 53, and 54 respectively. Suchclamping means, and the associated apparatus for actuating same, aredescribed elsewhere, herein, in detail.

For the purpose of sequentially rotating and stopping turntable 40 tosequentially index successive work pieces with the path of the broachingmeans, a chain 56 is driven by a gear '57 which is keyed to the lowersprocket shaft 30 as is best seen in Figure 3. Chain 56 drives a gear 58and a beveled gear 59 coaxially mounted on jackshaft 66 which shaft isjournaled in the frame 10. The beveled gear 59 in turn drives a beveledgear 62 which is keyed to a vertically extending shaft 63 journaled inframe top plate 44. A driving portion 65, of a Geneva drive mechanism,is keyed to the upper end of shaft 63, with the driving portion 65 beingin operational engagement with a driven portion 66 of the Geneva drive,said driven portion being keyed to the vertically extending shaft 42,which shaft rotatably mounts turntable 40 on the frame top plate 44- aspreviously described.

From the preceding description it will be seen that the work piecetransporting means, or turntable 40, is driven by the same variablespeed drive 34 and prime mover 35 which operates the broach transportingmeans since power for rotating turntable 40 is taken off of lowersprocket shaft 30. Hence, with the gear train described, the speed ofrotation of the work piece transporting means, or turntable 40, willalways be proportioned to the speed of travel of the broach.transporting means for any given speed at which the variable speed drive34 is operated. An important difierence exists,

however, in that the motion of the broach transporting means iscontinuous, due to the direct chain and sprocket drive, whereas themotion of the work piece transporting means, or turntable 40, consistsof intermittent rotary motion periods and stop positions due to the factthat the Geneva drive, portions 65 and 66, is provided in the drivemechanism for the work piece transporting means. Hence the turntable 49remains stationary for intermittent periods. During each period a workpiece can be inserted in the particular clamping means which isstationary at the loading station. For example, see clamping means 51 inFigure 6. At the same time another work piece is retained stationary inthe path of the broaching means by clamping means 53, and still anotherWork piece is either removed or objected from clamping means 54. Afterthe above mentioned operations have occurred, a stationary period forthe turntable 40 will automatically be terminated by the continuouslyoperating Geneva drive and turntable 40 will be rotated so that each ofthe clamping means 51, 52, 53, and 54 will be transported to the nextsuccessive station of rotation and the operations above described willbe performed on the work pieces newly presented at each station ofrotation.

Referring particularly to Figures 6 and 7 of the drawing, the clampingmeans 51, 52, 53, and 54, together with the associated apparatus forautomatically actuatting same, will next be described in detail. Aspreviously mentioned, clamping means 51 is shown at the loading stationand in open disposition. Such clamping means consists of a block 70which is provided with a slot shaped to register with 'the particularshape of the work piece to be broached. Block 70 is removably secured toturntable 40 so that said block can be removed and changed or replacedwhen the machine is to be retooled for a production run of work piecesof a different shape. Block 70 carries clamping lever 71 pivoted at 72,said lever being provided with a clamp 73 pivoted thereto at 74. Clamp73 may be shaped, in the tooling-up operation, so as to eflicientlyengage and position the work piece 46. A spring 75 may be provided fornormally urging clamping lever 71 towards the open position shown at theloading station.

To close clamping means 51, upon rotation of turntable 40 and after awork piece has been inserted, a suitable control power means is employedwhich may be in the form of the compressed air system best seen inFigures 6 and 7. An air reservoir 78 is mounted in stationarydisposition on the center of turntable 40. Since air reservoir 78rotates with turntable 40, a rotary fitting 80 is utilized at thejunction where air intake line 81 enters the reservoir 78. A pluralityof air outlet lines 83 extend radially from the base of air reservoir 78with each of said air outlet lines 83 extending to a respective camoperated air valve 84. Each of the air valves 84 includes a follower 85extending towards the axis of rotation of turntable 40. Air valves 84are each, in turn, connected by an air line 86 to a respective aircylinder 87 which cylinder includes a vertically extending plunger 88 inengagement with an end of a respective clamping lever 71 for actuatingsame to close the respective clamping means.

For the purpose of automatically and sequentially closing and openingthe Work piece clamping means 51, 52, 53, and 54 at the proper stationsof rotation of the turntable 40, a stationary cam 90, including a Tportion 91 and a heel portion 92, is disposed inwardly of the air valves84 and outwardly spaced from the air reservoir 78 as best seen inFigures 6 and 7. To support the cam 90 in the stationary position abovedescribed, an arm 95, including a cam mounting ring 96, is secured tothe frame 10 as seen in Figure 3 at 97.

Considering clamping means 51, which is shown in open disposition at theloading station, it will be seen that follower 85 is not, at suchstation, engaged and depressed by cam 90; hence the normally closed airvalve 84.is closed so that the air supply cannot actuate air cylinder87. Hence, clamping lever 71 is held in the open position by the spring75. Upon rotation of turntable 40, however, follower 85 advances andengages toe 91 of cam 90. The follower 85 is thereby depressed openingair valve 84 which permits air to pass from reservoir 78 to air cylinder87 whereby the clamping means 51 is immediately closed. Clamping means51 will next be sequentially advanced to the 90 degree station ofrotation, and then to the 180 degree station of rotation at which latterbroaching of the work piece 46 occurs. It will be seen, from Figure 6,that follower 85 will remain in depressed engagement with cam 90 up to,and slightly beyond, the 180 degree or broaching station. As soon asclamping means 51 is advanced to a position slightly beyond thebroaching station, follower 85 will leave cam 90 at heel portion 92. Airvalve 84 will thereby' be closed and air cylinder 87 ceases to applyforce to clamping lever 71. Clamping lever 71 then returns tothe" openposition due to the. action of spring 75 and remains open through thebalance of the cycle of rotation of the turntable. Hence it is seen thatwork pieces can be removed, or ejected, either at the 270 degree stationof rotation or after the clamping means has rotated through 360 degreesand returned to .the loading station; It is preferable, however, toautomatically eject the work pieces at the 270 degrees station ofrotation so'that the operator of the machine-need only be concerned withplacing a work piece in each successive clamping means as it stops inopen disposition at the loading station.

For the purpose of accurately positioning and locking the turntable 40at each of the stationary positions of rotation in order to eflectprecision broaching for close tolerance control, a turntable lockingmechanism is provided. Figure 5 is a schematic view of the variouselements of such locking mechanism including a beveled latch 101 adaptedto lockingly engage beveled slots in the periphery of the turntable 40as is best seen in Figures 3 and 6. Beveled latch 10 1 is guided andsecured to frame portion 100 by a guide member 102. A power cylinder 104normally urges the beveled latch 101 against the periphery of turntable40 such that beveled latch 101 will be caused to enter each beveled slotwhen the slot is advanced, by rotation of the turntable, to a positionconfronting the inwardly biased beveled latch 101.

To unlock the turntable, just prior to the ending of each stationaryperiod and after broaching has been effected, a control valve 106 ismounted to the frame adjacent to the path of travel of the broachingmeans 37 as shown in Figures 2 and 7. Control valve 106 includes an arm107 carrying a roller 108. Roller 108 extends into the path of and iscyclically engaged by the broaching means subsequent to each passage ofthe broaching means along the cutting path. Control valve 106 serves tocontrol the flow of fluid, such as air, to a power cylinder 104 throughlines 109 and 110. Hence upon actuation of arm 107, upon engagement ofroller 108 by the broaching means, fluid passage through lines 109 and110 energizes power cylinder 104 which serves to retract beveled latch101. The turntable 40 is thereby unlocked subsequent to passage of thebroaching means 37 through the cutting path and prior to advancement ofthe turntable 40 at the next station of rotation by the Geneva drive 65and 66. It is therefore seen that whereas the Geneva drive serves tosequentially rotate and stop the turntable at the successive stations,the turntable locking mechanism provides refined positioning means forprecision work piece location at the broaching station.

To further eifect precision broaching and close tolerance control, meansis provided for accurately guiding the broaching means 37 during itspassage along the cutting path at which time engagement with the workpiece occurs. Slide members 136 are secured to vertical side plates 18and 19 by machine screws 137. Caps 140 are secured to slide members 136and cooperate therewith to form guide slots 138. The entrance to guideslots 138 is beveled, as best seen in Figure 4, to effect entry thereinof broaching means 37 which includes a carriage 119 formed with arounded nose 120. Carriage 119 is conveyed by chain 21, which chain isefficient for its purpose, but not structurally adapted for effecting aprecisely located cutting path for the broaching means 37. A precisesliding fit, together with proper lubrication, is therefore providedbetween carriage 119 and guide slots 138. Due to the inherentflexibility of chain 21 the carriage 119 will not always be preciselypresented to guide slots 138. Hence the entrance to the slots isbeveled, as shown in Figure 4, to effect entry of broaching means 37into the precisely located cutting path defined by guide slots 138.

From the foregoing it will be understood that precision broaching isachieved by accurate location of the work pieces by means of theturntable locking mechanism, and by accurately locating and controllingthe cutting path of the broaching means.

With particular reference to the broaching means 37,,it will be seen,from. Figures 2 and 5, that carriage 119 is pivotally mounted to chain21 by pin 131 passing through flanges 128, which flanges straddle thechain 21 in the manner shown in Figure 3. Carriage 119 is also formedwith a third central flange 132 which extends forwardly from carriage119 to engage the preceding chain pin. The broaching means is travelingdownwardly towards the guide slots 138 as seen in Figure 5. In suchposition of broaching means travel the flange 132 serves to properlyposition the nose 120, of the pivotally mounted carriage 119, for entryinto guide slots 138.

For the purpose of removably securing a broach cutter to the carriage119', a slideably carried wedge block 122 is secured to stationary guideblock 121 by means of threaded fastening 124. Accurate positioning ofbroach cutter 125 can be effected by keying same to the wedge blocks.Hence it is seen that broach cutter 125 can be readily removed forretooling or replaced when worn.

In summary, from the foregoing description it will be understood thatthe present invention provides, a novel work piece transportingmechanism for effecting continuous broaching of multiple parts wherebysuch parts are broached at a faster rate and with more precise tolerancecontrol than has heretofore been obtainable by conventionalconstructions.

While the form of embodiment of the present invention as hereindisclosed constitutes a preferred form, it is to be understood thatother forms might be adopted, all coming within the scope of the claimswhich follow.

I claim:

1. An improved work piece transporting mechanism comprising a frame; acircular platform rotatable about a central axis; means forintermittently moving and stopping said platform; a plurality ofworkpiece clamping means mounted in spaced relationship on the peripheryof said platform and movable between open and closed positions; meansforming a source of pressurized fluid including a reservoir centrally ofsaid platform; a stationary cam mounted to said frame and disposedcentrally of said platform; a plurality of fluid actuated cylindersmounted on said table inwardly of said clamping means for moving each ofsaid clamping means towards one of said positions; a plurality ofradially extending conduit means each of which connects a respective oneof said cylinders with said reservoir; a plurality of valve means, eachof said valve means serving to control the flow of fluid in a respectiveone of said conduit means; and a plurality of actuators for said valvemeans, each of said actuators including a radially inwardly extendingfollower engageable with said cam.

2. An improved work piece transporting mechanism comprising a frame; acircular platform rotatable about a central axis; means forintermittently moving and stopping said platform; a plurality ofworkpiece clamping meansmounted in spaced relationship on the peripheryof said platform and movable between open and closed positions, each ofsaid clamping means comprising a pivoted lever including an end forreceiving a fixture for engaging a work piece; means forming a source ofpressurized fluid including a reservoir centrally of said platform; astationary cam mounted to said frame and disposed centrally of saidplatform; a plurality of fluid actuated cylinders mounted on said tableinwardly of said clamping means for moving each of said clamping meanstowards one of said positions, means of said cylinders including aplunger engaging a respective one of said levers; a plurality ofradially extending conduit means each of which connects a respective oneof said cylinders with said reservoir; a plurality of valve means, eachof said valve means serving to control the flow of fluid in a respectiveone of said conduit means; and a plurality of actuators for said valvemeans, each of said actuators including a radially inwardly extendingfollower engageable with said cam.

3. An improved work piece transporting mechanism comprising a frame; acircular platform rotatable about a central axis; means forintermittently moving and stopping said platform, said platformincluding a peripheral surface provided with a plurality ofcircumferentially spaced slots; a plurality of workpiece clamping meansmounted in spaced relationship on the periphery of said platform andmovable between open and closed positions; means forming a source ofpressurized fluid including a reservoir centrally of said platform; astationary cam mounted to said frame and disposed centrally of'saidplatform; a plurality of fluid actuated cylinders mounted on said tableinwardly of said clamping means for moving each of said clamping meanstowards one of said positions; a plurality of radially extending conduitmeans each of which connects a respective one of said cylinders withsaid reservoir; a plurality of valve means, each of said valve meansserving to control the flow of fluid in a respective one of said conduitmeans; a plurality of actuators for said valve means, each of saidactuators including a radially inwardly extending follower engageablewith said cam; a bolt mounted to said frame and engaging said peripheralsurface; means biasing said bolt inwardly against said surface and tocause said bolt to enter said slots; and means for withdrawing said boltfrom said slots.

References Cited in the file of this patent UNITED STATES PATENTS1,628,103 Best May 10, 1927 1,810,300 Spring June 16, 1931 2,122,356Bullard June 28, 1938

